A massive trench has been discovered under Antarctic ice by British researchers.

The experts say the ancient subglacial trough in the western part of Antarctica is deeper than the Grand Canyon.

It's called the Ellsworth Subglacial Highlands and is an ancient mountain range buried beneath several kilometres of Antarctic ice. The researchers from several U.K. universities made the discovery using data from satellites and ice-penetrating radars towed behind snowmobiles and installed on board small aircraft.

"To me, this just goes to demonstrate how little we still know about the surface of our own planet. The discovery and exploration of hidden, previously unknown landscapes is still possible and incredibly exciting, even now," lead study author Neil Ross, from Newcastle University, said in a release about the find.

The findings are published in the latest edition of the Geological Society of America Bulletin.